System and method for pre-charge protection circuit

Abstract

A method includes monitoring a voltage across a pre-charge circuit of a drive module disposed within an industrial automation system, wherein the pre-charge circuit is configured to reduce current flowing from a power source to a plurality of capacitors when the drive module is powered on, identifying when the voltage across the pre-charge circuit exceeds a threshold value for more than a threshold period of time, and in response to the voltage across the pre-charge circuit exceeding the threshold value for more than the threshold period of time, opening a pre-charge switch and a pre-charge bypass switch to prevent current from flowing from the power source into the pre-charge circuit and the plurality of capacitors of the drive module.

1 . A drive module configured to control operation of a motor in an industrial automation system, the drive module comprising:
 a plurality of capacitors;   a pre-charge circuit comprising one or more resistors and a pre-charge switch that electrically couples the pre-charge circuit to the plurality of capacitors, wherein the pre-charge circuit is configured to reduce current flowing from a power source to the plurality of capacitors when the drive module is powered on;   a bypass switch comprising a contactor, solid switch, relay, or any combination thereof, configured to close after the plurality of capacitors are charged, bypassing the pre-charge circuit; and   a pre-charge protection circuit configured to, in response to a voltage across the pre-charge circuit exceeding a threshold value for more than a threshold period of time, open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit.   
     
     
         2 . The drive module of  claim 1 , wherein the pre-charge protection circuit is configured to, in response to one or more of a plurality of respective voltages of the plurality of capacitors exceeding an additional threshold value for more than an additional threshold period of time, open the pre-charge switch and the bypass switch to prevent the current from flowing into the plurality of capacitors and the pre-charge circuit. 
     
     
         3 . The drive module of  claim 2 , wherein the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the additional threshold value for more than the additional threshold period of time is indicative of a fault within the drive module. 
     
     
         4 . The drive module of  claim 2 , wherein the drive module comprises:
 a capacitor voltage sensing circuit configured to monitor the plurality of respective voltages of the plurality of capacitors and output a first signal indicative of one or more of the plurality of respective voltages of the plurality of capacitors; and   a main control board configured to receive the first signal and provide a second signal to the pre-charge protection circuit to open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit in response to the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the additional threshold value for more than the additional threshold period of time.   
     
     
         5 . The drive module of  claim 4 , wherein the pre-charge protection circuit comprises a capacitor overvoltage signal circuit configured to:
 receive the first signal from the capacitor voltage sensing circuit; and   output a third signal to open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit in response to the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the additional threshold value for more than the additional threshold period of time.   
     
     
         6 . The drive module of  claim 1 , wherein the pre-charge protection circuit comprises a control power circuit configured to receive an input voltage and provide power to the pre-charge protection circuit based on the input voltage. 
     
     
         7 . The drive module of  claim 6 , wherein the pre-charge protection circuit comprises a pre-charge input voltage sensing circuit configured to output a signal indicative of a voltage across the pre-charge circuit, wherein the voltage across the pre-charge circuit comprises a difference between the input voltage to the pre-charge circuit and an output voltage of the pre-charge circuit. 
     
     
         8 . The drive module of  claim 7 , wherein the pre-charge protection circuit comprises a pre-charge protection control circuit configured to:
 receive, from the pre-charge input voltage sensing circuit, the signal indicative of the voltage across the pre-charge circuit;   in response to the voltage across the pre-charge circuit being below the threshold value, outputting a second signal to allow the current to flow from the power source into one or more of the plurality of capacitors; and   in response to the voltage across the pre-charge circuit being above the threshold value for more than a further threshold period of time, outputting a third signal to prevent the current from flowing from the power source into the one or more of the plurality of capacitors.   
     
     
         9 . The drive module of  claim 8 , wherein the pre-charge protection circuit comprises a pre-charge bypass signal circuit configured to:
 receive the second and third signals from the pre-charge protection control circuit; and   output a fourth signal to enable or disable the bypass switch based on receiving the second signal or the third signal.   
     
     
         10 . The drive module of  claim 1 , wherein the pre-charge protection circuit comprises a gating circuit configured to control the pre-charge switch. 
     
     
         11 . An industrial automation system, comprising:
 a motor coupled to a load; and   a drive module configured to receive power from a power source and control operation of the motor, wherein the drive module comprises:
 a plurality of capacitors; 
 a pre-charge circuit comprising one or more resistors and a pre-charge switch that electrically couples the pre-charge circuit to the plurality of capacitors, wherein the pre-charge circuit is configured to reduce current flowing from the power source to the plurality of capacitors when the drive module is powered on; 
 a bypass switch comprising a contactor, solid switch, relay, or any combination thereof, configured to close after the plurality of capacitors are charged, bypassing the pre-charge circuit; and 
 a pre-charge protection circuit configured to, in response to a voltage across the pre-charge circuit exceeding a first threshold value for more than a first threshold period of time, one or more of a plurality of respective voltages of the plurality of capacitors exceeding a second threshold value for more than a second threshold period of time, or both, open the pre-charge switch and the bypass switch to prevent the current from flowing into the plurality of capacitors and the pre-charge circuit. 
   
     
     
         12 . The industrial automation system of  claim 11 , wherein the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the second threshold value for more than the second threshold period of time is indicative of a fault within the drive module. 
     
     
         13 . The industrial automation system of  claim 11 , wherein the drive module comprises:
 a capacitor voltage sensing circuit configured to monitor the plurality of respective voltages of the plurality of capacitors and output a first signal indicative of one or more of the plurality of respective voltages of the plurality of capacitors; and   a main control board configured to receive the first signal and provide a second signal to the pre-charge protection circuit to open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit in response to the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the second threshold value for more than the second threshold period of time.   
     
     
         14 . The industrial automation system of  claim 13 , wherein the pre-charge protection circuit comprises a capacitor overvoltage signal circuit configured to:
 receive the first signal from the capacitor voltage sensing circuit; and   output a third signal to open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit in response to the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the second threshold value for more than the second threshold period of time.   
     
     
         15 . The industrial automation system of  claim 11 , wherein the pre-charge protection circuit comprises:
 a control power circuit configured to receive an input voltage and provide power to the pre-charge protection circuit based on the input voltage;   a pre-charge input voltage sensing circuit configured to output a first signal indicative of a voltage across the pre-charge circuit, wherein the voltage across the pre-charge circuit comprises a difference between the input voltage to the pre-charge circuit and an output voltage of the pre-charge circuit;   a pre-charge protection control circuit configured to receive, from the pre-charge input voltage sensing circuit, the first signal indicative of the voltage across the pre-charge circuit, in response to the voltage across the pre-charge circuit being below the threshold value, outputting a second signal to allow the current to flow from the power source into one or more of the plurality of capacitors, and in response to the voltage across the pre-charge circuit being above the threshold value for more than a third threshold period of time, outputting a third signal to prevent the current from flowing from the power source into the one or more of the plurality of capacitors; and   a pre-charge bypass signal circuit configured to receive the second and third signals from the pre-charge protection control circuit, and output a fourth signal to enable or disable the bypass switch based on receiving the second signal or the third signal.   
     
     
         16 . A method, comprising:
 monitoring a voltage across a pre-charge circuit of a drive module disposed within an industrial automation system, wherein the pre-charge circuit is configured to reduce current flowing from a power source to a plurality of capacitors when the drive module is powered on;   identifying when the voltage across the pre-charge circuit exceeds a threshold value for more than a threshold period of time; and   in response to the voltage across the pre-charge circuit exceeding the threshold value for more than the threshold period of time, opening a pre-charge switch and a pre-charge bypass switch to prevent current from flowing from the power source into the pre-charge circuit and the plurality of capacitors of the drive module.   
     
     
         17 . The method of  claim 16 , comprising:
 monitoring a plurality of respective voltages of the plurality of capacitors of the drive module disposed within the industrial automation system;   identifying when one or more of the plurality of respective voltages of the plurality of capacitors exceeds an additional threshold value for more than an additional threshold period of time; and   in response to the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the additional threshold value for more than the additional threshold period of time, opening the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit.   
     
     
         18 . The method of  claim 17 , comprising:
 receiving, via a main circuit board, from a capacitor voltage sensing circuit, a first signal indicative of one or more of the plurality of respective voltages of the plurality of capacitors; and   providing a second signal to open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit in response to one or more of the plurality of respective voltages of the plurality of capacitors exceeding the additional threshold value for more than the additional threshold period of time.   
     
     
         19 . The method of  claim 18 , comprising:
 receiving, via a capacitor overvoltage signal circuit, the first signal from the capacitor voltage sensing circuit; and   outputting, via the capacitor overvoltage signal circuit, a third signal to open the pre-charge switch and the bypass switch to prevent the current from flowing from the power source into the plurality of capacitors and the pre-charge circuit in response to the one or more of the plurality of respective voltages of the plurality of capacitors exceeding the additional threshold value for more than the additional threshold period of time.   
     
     
         20 . The method of  claim 16 , comprising:
 receiving, via a control power circuit, an input voltage;   providing, via the control power circuit, power based on the input voltage;   outputting, via a pre-charge input voltage sensing circuit, a first signal indicative of a voltage across the pre-charge circuit, wherein the voltage across the pre-charge circuit comprises a difference between the input voltage to the pre-charge circuit and an output voltage of the pre-charge circuit;   receiving, from the pre-charge input voltage sensing circuit, the first signal indicative of the voltage across the pre-charge circuit;   in response to the voltage across the pre-charge circuit being below the threshold value, outputting a second signal to allow the current to flow from the power source into one or more of the plurality of capacitors;   in response to the voltage across the pre-charge circuit being above the threshold value for more than the threshold period of time, outputting a third signal to prevent the current from flowing from the power source into the one or more of the plurality of capacitors;   receiving the second and third signals from a pre-charge protection control circuit; and   outputting a fourth signal to enable or disable the bypass switch based on receiving the second signal or the third signal.